Recessed light fixtures are commonplace in residential homes and commercial buildings. A recessed light fixture typically has a metal housing or can, an electrical junction box, and a conical-shaped recessed trim assembly to direct and reflect the lighting emitted by a bulb (or similar light source) that is held inside by a bulb holder or socket. The can and junction box are supported on a pan. The can and pan assembly are installed above the ceiling of a building or house so that the opening in the can and the trim are flush with the ceiling. The light fixture is thus recessed into the ceiling. The light source inside the trim assembly can be an incandescent or halogen bulb, a compact fluorescent tube (CFL), an LED or the like.
A decorative trim ring is often attached to the trim assembly of the light fixture facing the floor, exposed to the living space beneath the fixture. The trim ring provides a finished look for the light fixture.
The can, trim assembly, junction box and pan are suspended by a pair of hanger bars extending parallel and on opposite sides of the pan. One type of standard ceiling is supported by joists, and the recessed light fixture is mounted onto the joists via the hanger bars. When the joists are made of wood or concrete, for example, the hanger bars are usually mounted to the joists with nails, screws or other standard mounting means. The weight of the light fixture is thereby supported by the joists through the hanger bars.
Alternatively, the ceiling may be of the “drop-down” or suspended type. A drop-down ceiling is a secondary ceiling often formed to conceal piping, wiring, HVAC, and/or the floor above. The drop-down ceiling typically consists of a grid-work of metal channels in the shape of an upside-down “T” (i.e., T-bar grid), suspended on wires from an overhead structure. The channels snap together in a regularly spaced pattern, and the resulting cells are filled with lightweight “acoustic ceiling tiles” or “panels” dropped into the grid. Light fixtures may be installed into the grid as desired.